1. Field of the Invention
This invention relates to ladders used primarily for recreational vehicles, and particularly to the ladder step construction and its method of fastening to the ladder rails.
2. Description of the Prior Art
In the traditional method of ladder assembly, the steps are fastened by long cantilevered screws that go through the end cap, an air space and then through both walls of the rail tubing. This places great shear stress on the long unsupported screws. Such an arrangement is typically used in U.S. Pat. No. 4,193,477 by Broyles and others. There are also numerous methods of fastening the ladder steps to the rails such as utilizing forced fit and metal flow, or by fitting the ends of each step to the rails and swaging or welding them. In a few cases, end caps are used to protect the inner surfaces of the steps from corrosion. In the Broyles invention, the end caps are screwed into the step and form part of the fastening mechanism.
In order to produce the necessary stiffness and strength required to support heavy loads, the step constructions used in the past are relatively heavy, or of intricate cross-section and manufacture, often presenting problems in fabrication and durability. Thus, there exists a need for a ladder step construction which is at once light, strong, simple in fabrication and durable in use.